Writing a good story is hard. Making a good video game is hard. Trying to make a good video game that also tells a good story is damned near impossible.
Not that they don't try. Video game makers are working hard to achieve their dream of a playable movie, or at least a game that looks like a movie in a two-minute trailer. But when you're playing the games, that "I'm in the movie! Whee!" illusion disappears as soon as you hear things like...
5"Hey, Nico! Instead of hijacking that armored truck, let's go bowling!"
In Grand Theft Auto 4, your average GTA player's thought process generally flows something like this in-game:
1. Steal a car
2. Find old lady
3. Run over old lady
4. Sex with hooker
5. Run over hooker
6. Grab Hot Pocket from microwave
7. Kill some cops
8. Visit car wash to get old lady and hooker bits out of stolen car's grille.
...and so on. If you were to follow that thought process from start to finish, not once would you see the words "I want to watch my fat cousin eat." But guess what you had to do, frequently, over the course of the game?
"Ooh! I know!"
And it wasn't just your cousin, oh no. Thanks to the relationship minigames they decided to include, practically every hard-bitten gangbanger you came across turned out to have abandonment issues, copious amounts of free time and a love of pool and darts that bordered on fetishistic.
I'd rather be playing darts.
The girls in the game are even more high-maintenance; bailing out on the relationship if you don't take them out often enough, or ramp your car into the river just once during a date. Though they can't hold a candle to the women you're supposed to "marry" in Fable 2. People have made detailed How-To Guides on how to stop a woman from divorcing you in that game (hint: get ready to spend lots of time gathering gifts and being romantic with her).
Seems Like a Good Idea Because...
It's just like the lovable characters in a good novel or, even better, real-life friends! What better way to add depth and drama to a game?
Doesn't Work Because...
We do favors for friends in real life because we enjoy their company. They're never going to code a video game character who'll give us anything like the feeling we get from human companionship, and it's probably unfair to expect them to. Instead it becomes a bunch of tedious minigames played with a robot who only knows 10 pre-recorded phrases, done purely out of an artificial sense of obligation.
It's Sort of Like...
Spending time with your in-laws during the holidays.